Convenient Synthesis of Spiro[benzo[d]pyrrolo[2,1‐b]thiazole‐3,2′‐indenes] Derivatives via Three‐Component Reaction

Abstract

The three-component reaction of N-phenacylbenzothiazolium bromides, aromatic aldehydes and indane-1,3-dione in ethanol at room temperature in the presence of triethylamine as base afforded functionalized spiro [benzo-[d]pyrrolo[2,1-b]thiazole-3,2'-indenes] in good yields and with high diastereoselectivity. The 1 H NMR data and single crystal structure clearly indicated that the obtained spiro compounds predominately have one diastereoisomer.

Domino Reaction of Aromatic Aldehydes and 1,3-Indanediones for Construction of Bicyclo[2.2.2]octanes and Dibenzo[b,g]indeno[1′,2′:3,4]fluoreno[1,2-d]oxonines

“…It has been well known that the base-promoted reaction of aromatic aldehydes and 1,3-indanedione in common organic solvents resulted in 2-arylidene-1,3-indanedione in high yields. In our continuous investigations of multicomponent reactions of 1,3-indanedione to prepare diverse fused and spiro-heterocyclic compounds, , a unique polycyclic compound 1a was obtained in 31% yield when 4-tolualdehyde was mixed at room temperature with 4.4 equiv. of 1,3-indanedione in ethanol in the presence of triethylamine (entry 1, Table ).…”

“…On the other hand, the easily prepared 2-arylidene-1,3-indanediones are also typical 1,3-dipolarophiles and dienophiles. 2-Arylidene-1,3-indanediones have been widely employed in many Michael addition, condensation reaction, Diels–Alder reaction, cyclization reaction, and domino multicomponent reactions. − In recent years, we have successfully developed several efficient multicomponent reactions for construction of diverse spiroindanones by employing readily available 1,3-indanedione and 2-arylidene-1,3-indanediones as key substrates. , In these research works, we gradually noticed that 1,3-indanedione showed versatile reactivity in multicomponent reactions depending on the reaction conditions …”

Stepwise cycloaddition reaction of N-phenacylbenzothiazolium bromides and nitroalkenes for tetrahydro-, dihydro- and benzo[d]pyrrolo[2,1-b]thiazoles

“…We began our investigation by carrying out the reaction of N -phenacylbenzothiazolium bromides with nitroalkenes according to our previously established base promoted procedure 37 38 . When a mixture of N -(4-methylphenacyl)benzothiazolium bromide with 1-nitro-2-( p -methoxyphenyl)ethene in ethanol with triethylamine as base was stirred at room temperature, the reaction can be finished in four hours to give the expected tetrahydrobenzo[ d ]pyrrolo[2,1- b ]thiazole 1a in very high yield.…”

“…In this respect, besides most common using imidazolium ylides, pyridinium ylide and isoquinolinium ylides, the 1,3-dipolar cycloaddition of thiazolium ylides or benzothiazolium ylides were also employed for preparing some pyrrolo[2,1- b ]thiazole and its bezno- derivatives 29 30 31 32 33 34 35 36 . Recently, we found that the 1,3-dipolar cycloadidtion reaction of base mediated N -phenacylbenzothiazolium bromides with 3-methyleneoxindoles afforded spiro[benzo[ d ]pyrrolo[2,1-b]thiazole-3,3′-indolines] in good yields and with high diastereoselectivity 37 . Similarly, the base promoted three-component reaction of N -phenacylbenzothiazolium bromides, aromatic aldehydes and indane-1,3-dione resulted in functionalized spiro[benzo[ d ]pyrrolo[2,1- b ]thiazole-3,2′-indenes] 38 .…”

Diastereoselective Desymmetrization of Prochiral Cyclopentenediones via Cycloaddition Reaction with N-Phenacylbenzothiazolium Bromides

“…A wide variety of 1,3 diploar cycloaddition have been developed employing these azo-methine ylides and products such as polysubstituted pyridines, terpyridines and indolizines were obtained . We became interested particularly in the cycloaddition reactions with N -phenacylbenzothiazolium bromides as the resulting products are different derivatives of benzothiazoles and could be potentially bioactive. Though different olefinic dipolarophiles were employed previously in the cycloaddition reaction with N -phenacylbenzothiazolium bromides, to the best of our knowledge, no report on desymmetrization reaction with a meso or prochiral dipolarophile has been documented.…”